High-carbon steel wire rod of high ductility

Abstract

A high-carbon steel wire rod of high ductility for steel cord and the like is provided that experiences little breakage during drawing. The high-carbon steel wire rod of high ductility is a high-carbon steel wire rod fabricated by hot rolling that that has a carbon content of 0.7 mass % or greater, wherein 95% or greater of the wire rod metallographic structure is pearlite structure and the maximum pearlite block size of pearlite at the core of the hot-rolled wire rod is 65 μm or less. The high-carbon steel wire rod of high ductility has a tensile strength in a range of {248+980×(C mass %)}±40 MPa} and a reduction of area of {72.8−40×(C mass %) %} or greater. The high-carbon steel wire rod of high ductility is characterized in that the average pearlite block size at the core of the hot-rolled wire rod constituted by ferrite grain boundaries of an orientation difference of 9 degrees or greater as measured with an EBSP analyzer is 10 μm or greater and 30 μm or less.

1 . A high-carbon steel wire rod of high ductility, which is a high-carbon steel wire rod having a carbon content of 0.7 mass % or greater, wherein 95% or greater of the wire rod metallographic structure is pearlite structure and maximum pearlite block size at a core of a cross-section perpendicular to the wire rod axis is 65 μm or less. 
   
   
       2 . A high-carbon steel wire rod of high ductility according to  claim 1 , having a tensile strength in a range of {248+980×(C mass %)}±40 MPa} and a reduction of area of {72.8−40×(C mass %) %} or greater. 
   
   
       3 . A high-carbon steel wire rod of high ductility according to  claim 1 , wherein an average pearlite block size at the core of the cross-section perpendicular to the wire rod axis is 10 μm or greater and 30 μm or less. 
   
   
       4 . A high-carbon steel wire rod of high ductility according to  claim 1 , wherein the wire rod metallographic structure includes pro-eutectoid ferrite at a volume percentage of 2% or less. 
   
   
       5 . A high-carbon steel wire rod of high ductility according to  claim 1 , wherein the wire rod comprises, in mass %, C: 0.7 to 1.1%, Si: 0.1 to 1.0%, Mn: 0.1 to 1.0%, P: 0.02% or less, S: 0.02% or less, and a balance of Fe and unavoidable impurities. 
   
   
       6 . A high-carbon steel wire rod of high ductility according to  claim 5 , wherein the wire rod further comprises, in mass %, one or more of Cr: 0.05 to 1.0%, Mo: 0.05 to 1.0%, Cu: 0.05 to 1.0%, Ni: 0.05 to 1.0%, V: 0.001 to 0.1%, Nb: 0.001 to 0.1%, Ti: 0.005 to 0.1%, B: 0.0005 to 0.006%, O: 18 to 30 ppm, and N: 0 to 40 ppm.